000
FXUS63 KEAX 012331
AFDEAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
631 PM CDT SAT AUG 1 2015
.DISCUSSION...
Issued at 352 PM CDT SAT AUG 1 2015
Isolated thunderstorms will continue this afternoon in an area of
generally uncapped, 3000-5000 J/kg CAPE and broad isentropic lift in
the 310-315 K surface. No real upper-level forcing is discernible
and multiple outflow boundaries have developed/settled across the
region, so development will be scattered and somewhat random
throughout the majority of the area over the next several hours. The
environment is quite supportive of downburst winds, and have seen up
to 50 mph winds with the strongest cells as they collapse, as well
as small hail. These hazards will continue to exist due to extreme
CAPE and downdraft CAPE in excess of 1000 J/kg. Shear is marginal at
best, supporting pulsy storms and motion driven mostly by cold pool
dynamics. In addition to the isolated storms, excessive heat will
also be a concern this afternoon as dewpoints have risen into the
lower to even mid 70s, combining with temperatures in the 80s to low
90s and bringing heat indices into the upper 90s to lower 100s area-
wide.
As instability begins to diminish this evening, storms should
dissipate gradually throughout the forecast area. Additional storms
may develop again tonight into early Sunday morning across eastern
Nebraska where a shortwave trough will pass over the persistent weak
baroclinic zone, but should develop far enough north and travel with
enough of an eastward fetch to remain mainly north of the CWA. If
storms throw out an outflow boundary or begin to drive southward due
to their cold pool they may edge into the CWA after midnight, so
have kept the slight chance PoPs in our north tonight. The best
probability for this to occur will be in northeast MO after 09z, so
have kept slightly higher PoPs in this area toward early morning.
On Sunday afternoon and evening, the weak frontal boundary that has
persisted over eastern Nebraska will finally begin to drift
southward, possibly sparking a few showers and storms as it sinks
through the forecast area. Have kept some lower-end chances of
storms from the afternoon through the overnight hours; however, the
better dynamics still look east of the region and therefore expect
storms to be isolated if they develop. Temperatures and instability
will be quite high south of the stalled boundary during the day, and
moisture pooling along/ahead of the boundary will push heat indices
to near 100 degrees again in areas south of the front.
The boundary will stall in the vicinity of I-70 on Monday, lingering
in the area and providing continuous thunderstorm chances through at
least Tuesday. A shortwave trough will slide through the region
Tuesday or Tuesday night and enhance precipitation chances, and will
also lay out another frontal boundary that will remain through the
end of the work week keep thunderstorm chances between 30-50%
through the rest of the period. Temperatures will be slightly lower
due to cloud cover and periods of precipitation, but will likely
still be quite muggy on the south side of the front.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 627 PM CDT SAT AUG 1 2015
VFR conditions expected through the period. Convection to the east
should dissipate as the evening progresses. The associated outflow
boundary with these storms will turn winds to the east temporarily,
before southwesterly winds resume through the remainder of the
period. Overnight convection is possible near KSTJ, but the majority
of this activity should remain to the north of the area.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
DISCUSSION...Laflin
AVIATION...Welsh